<div ng-switch on="info.type">
    <!-- 欢迎消息 -->
    <div class="system-notification" ng-switch-when="welcome">
        <strong>系统:&nbsp;&nbsp;</strong><span>{{info.content}}</span>来啦,大家不要放过他~
    </div>
    <!-- 退出消息 -->
    <div class="system-notification" ng-switch-when="bye"><strong>系统:&nbsp;&nbsp;</strong>byebye,
        <span>{{info.content}}</span></div>
    <!-- 普通消息 -->
    <div class="normal-message" ng-class="{others:self!==info.from,self:self===info.from}" ng-switch-when="normal">
        <!-- ng-class是根据 key: value来设置class -->
        <div class="name-wrapper"><span>{{info.from}} @ </span><span>{{time |  date: 'HH:mm:ss' }}</span></div>
        <div class="content-wrapper"><span class="content">{{info.content}}</span><span class="avatar"></span></div>
    </div>
</div>
